Gas bonding - is my incoming gas pipe PE?

[JohnW2]

No, you misunderstand as well. If a part is not earthed in any way, then you cannot bond it. ... The process would be earthing .....

Hmmm - this is getting very semantic/academic, not really of much, if any, practical consequence.

If one wants to be pedantic, as you know,, BS7671 requires all extraneous-c-ps to be main bonded, and its definition of an extraneous-c-p includes the phrase "... liable to introduce a potential, generally Earth potential ... ", so, strictly speaking, something does not have to be 'earthed' for main bonding of it to be required.

Even more pedantically, if a conductive part entering a building is electrically 'floating', then it could well have 'a potential' (but not Earth potential) due to capacitive and/or coupling - and so, 'strictly speaking' would need to be bonded.

.... The process would be earthing - then you could bond it.

I'm not so sure about that. Whilst I accept that the definition of extraneous-c-p does not say this explicitly, in common sense terms they are talking about a conductive part that can introduce a potential other than that of the installation's earthing system (i.e. MET). Hence, if one 'earths' something by connecting it to the installation's MET, that does not (in common sense terms) turn the something into an extraneous-c-p (which can 'then be bonded').

 

[footprints]

"So, no bonding of sparrows, pigeons etc....?"

Wood pigeons are extra safe!

 

[ebee]

'Cross-bonding' is no longer required.

"cross bonding, if required, is actually supplementary bonding no more no less.

 

[JohnW2]

"cross bonding, if required, is actually supplementary bonding no more no less.

Supplementary bonding involves the connection of all simultaneously touchable extraneous-c-ps and exposed-c-ps.

The sort of 'cross-bonding' I was thinking/talking about (a lot of which I inherited in my present house, many moons ago!) usually consists of the connecting together of pipes and other conductive things (like sinks/baths etc., not being part of the electrical installation), none of which are usually either exposed-c-ps or extraneous-c-ps.

 

[plugwash]

And there are situations in which that sort of bonding is appropriate, but in a system involving only low frequencies at normal mains voltages, the modern thinking is it does more harm than good.

 

[JohnW2]

And there are situations in which that sort of bonding is appropriate, but in a system involving only low frequencies at normal mains voltages, the modern thinking is it does more harm than good.

Agreed.

 

[ebee]

Supplementary bonding involves the connection of all simultaneously touchable extraneous-c-ps and exposed-c-ps.

The sort of 'cross-bonding' I was thinking/talking about (a lot of which I inherited in my present house, many moons ago!) usually consists of the connecting together of pipes and other conductive things (like sinks/baths etc., not being part of the electrical installation), none of which are usually either exposed-c-ps or extraneous-c-ps.

Yep but by definition any sort of "cross bonding" is actually supplementary bonding. we are taught by the great and good that bonding has only two types though - Main and Supplementary.
Supplementary is not deliberately connected back to the MET itself, in bathrooms etc it is connected to the cpc of bathroom circuits as well as any relevant pipework etc.
If, for instance, a kitchen sink and pipework or boiler pipework etc needs such (kitchen sink and pipework used to be required in most instances a few years back but not nowadays, usually) then it is only those local parts, it was not necessary to connect to the cpc of kitchen lighting or kitchen power etc. The kitchen itself was never a zone for it but a few limited things in a small area, such as kitchen sink, might or might not have been.

Thinking changes, is bonding safer or not? well that answer can often be different in differing circumstances and we tend to decide that based on probability the best of the answers to particular scenarios. Swingy Roundabouts quite often the case. Do the most good and the least harm as far as we judge reasonable.

 

[EFLImpudence]

Yep but by definition any sort of "cross bonding" is actually supplementary bonding.

What is the definition of "cross" in this usage?

"Supplementary" just means "additional". It does not mean "cross" in any way.
It is not a type of bonding. It is simply additional to the main bonding conductor.

If someone wanted supplementary lighting would that mean a certain type of luminaire?

we are taught by the great and good that bonding has only two types though - Main and Supplementary.

As I said they are not types. You have the main bonding conductor and additional bonding conductors.

Supplementary is not deliberately connected back to the MET itself, in bathrooms etc it is connected to the cpc of bathroom circuits as well as any relevant pipework etc.

It is but that is because that is what is needed to achieve the desired effect; not because that is what supplementary means.

If, for instance, a kitchen sink and pipework or boiler pipework etc needs such (kitchen sink and pipework used to be required in most instances a few years back but not nowadays,

Did they? Did they used to be extraneous-conductive-parts but are not now?

usually) then it is only those local parts, it was not necessary to connect to the cpc of kitchen lighting or kitchen power etc. The kitchen itself was never a zone for it but a few limited things in a small area, such as kitchen sink, might or might not have been.

Thinking changes, is bonding safer or not? well that answer can often be different in differing circumstances and we tend to decide that based on probability the best of the answers to particular scenarios. Swingy Roundabouts quite often the case. Do the most good and the least harm as far as we judge reasonable.

All earthing is a compromise.

It would be better if nothing needed earthing but as it is we need equipotential bonding in some places as well.

 

[JohnW2]

Yep but by definition any sort of "cross bonding" is actually supplementary bonding. ....

Hmmm. In terms of everyday English, it's obviously supplementary' to any other sort of bonding, but I don't think what you say is correct in terms of recent editions of BS7671. ...

we are taught by the great and good that bonding has only two types though - Main and Supplementary.

I'm not sure where in the regs one can find that "only". BS7671 defines Main Bonding, and Supplementary Bonding (defined as interconnecting simultaneously-touchable exposed-c-ps and extraneous-c-ps), but I can recall no claim that those two represent an exhaustive list.

There is no reason why current and recent editions of BS7671 need to say anything about (let alone 'give a name to') bits of G/Y cable which connect things which are neither extraneous-c-ps nor exposed-c-ps.

Supplementary is not deliberately connected back to the MET itself, in bathrooms etc it is connected to the cpc of bathroom circuits as well as any relevant pipework etc.

Indeed - and, as I've said, the sort of "cross-bonding" I've been talking about is not (explicitly) connected to any CPCs, let alone the MET.

Thinking changes, is bonding safer or not? well that answer can often be different in differing circumstances ....

I don't think that the 'aim of bonding', per se, can ever be dangerous, since it merely equalises potentials. However, if one or more (but not all) of the bonded items is/are connected to earth, then the bonding results in the 'unnecessary earthing' of things that were not previously earthed and,as often discussed, that can result in a reduction in 'safety' (to be balanced against any benefits of having the bonding.).

 

[ericmark]

I would say that @JohnW2 has answered most of the questions, before the RCD back I think around the 14th edition we went mad on bonding, but two things, one as John has said, if the sink is not bonded the shock will be less current, so often it is better not to bond, the second very revenant with a gas pipe, is you don't want a high fault current to pass down the gas pipe, as if enough to melt the gas pipe, it would cause a fire.

So some where on the gas supply we need an insulating part, so the earth bonding is not connected to a metal pipe which can conduct enough current to melt, so bonding as the pipe enters the house, is likely not going to connect the metal incoming gas pipe to the PEN, with a TN-C-S earthing system.

Two supplies should not have their earths interconnected, this can be a problem with metal frame buildings where there are multi-supplies to the same building, really TN-C-S in my option should be banned, but it should not be used with a metal framed building.

We have a problem, an air line has been fitted between two buildings, it is made of steel, and it connects the earth systems of two independent step down transformers, so the current could be quite high, but a 3" steel pipe will take a lot of current, and likely the railway lines also connect the earths together, so it is unlikely there will be a problem, and anyway air does not tend to burn.

When all the water and gas pipes were metal, any fault current due to loss of PEN would be shared between the service pipes, so no pipe carried excessive current, it is as pipes are changed to plastic when the problems arises, as any pipe which is still steel or copper, will end up carrying the fault current on its own.

Water pipes tend to be water cooled, it is only the gas pipe which can be a problem. I don't have gas, so no worries, but only the gas men/women know if the incoming pipe is plastic or not, and if the pipe has an insulating block or not.

It's not that they don't accept it, they are not the "experts" on electrics. They are required, by law, to notify you that it should be checked by a competent person if it might be necessary.

The question is who is the competent person, the gas man or the electrician? The kit to test if an electrode is earthed and a metal gas pipe is an electrode is this

I have used them many times, but it is not the sort of kit normally carried by electricians, if we can measure the resistance of the gas pipe, we can calculate how much current under fault conditions it will carry, so at say 46Ω at 230 volt it will carry a maximum of 5 amp. But I have no idea how much a gas pipe can carry, and the gas pipe could easy be 4.6Ω now looking at 50 amp, there is no fuse on the PEN conductor, the RCD does not disconnect it, so the electrician simply does not have the information to know if there is a insulator in the gas supply. So all he can do is connect to an earth terminal provided by the gas man. Failing that earth bond inside the house and cross ones fingers there is an insulator.

 

[Taylortwocities]

TLDR

 

[ebee]

Eric mentioned Earth Bonding, at seminars by NICEIC etc I have heard them say that the term is incorrect, the correct term is Bonding - Main Bonding.
I actually disagree with them - the term we were told to use a relatively hort few years ago was EEBADS (or EEBADOS).
Well to me as the words "Earth" and "Bonding" in those abbreviations were present together so why not, as a shortform, call it "Earth Bonding"? It connects robustly together all incoming services that can reasonably be expected to pick up a potential from the earth around us and we deliberately clamp it all together in equalise all these potentials as far as reasonably practicable. So, Gas, Water, Oil, pipes etc and any structural metal and the installation earth terminal (whether that is derived from/near to a substation that might sometimes be quite a distance away therefore quite a potential voltage away from the ground beneath our feet. Likewise large slabs of damp concrete too.
If someone uses the term "Earth Bonding" I would not take them to task with it.

If we Main Bond as one thing and all other sorts of bonding are supplementary bonding, you might be linking across several different pipes to, example, a boiler of some sort, additionally you might be linking to the c.p.c of some boilers and again you might be ling to the c.p.cs of other circuits in that location. That is all supplementary bonding, because it is bonding that is not main bonding. If we stick to the two terms we know it is bonding and which type it is, indeed we might have a IT system that has supp bonding but not have main bonding.

Surely it is better and less likely to deceive or be misconstrued for as to have just the two types? and if someone wants to call Main Bonding Earth Bonding instead then I can live with that and if someone calls it cross bonding instead of supp bonding then personally I will usually know what they mean but it should be recognised that there are only two types therefore really only those to terms be used when discussing bonding.

John said
"The sort of 'cross-bonding' I was thinking/talking about (a lot of which I inherited in my present house, many moons ago!) usually consists of the connecting together of pipes and other conductive things (like sinks/baths etc., not being part of the electrical installation), none of which are usually either exposed-c-ps or extraneous-c-ps."

I says, yes there may or there may not be c.p,cs connected but in either case it is supp bonding if it is not main bonding.
And I think EFLI is saying much the same thing as John too.

K.I.S.S. Main or supp you often have both.

Main Bonding is often 10.0mm or above.
Supp bonding is to be worked out by a little formula but hey using that formula and the rules with it then it often works out as 4.0mm or above.
There is usually nothing to stop you using one looped conductor of say 10.0mm or above to satisfy both functions if you prefer but it is not necessary either, it would probably render it more time consuming an more expensive too.
(Well I can`t think of a situation where 4.0mm supp bonding is required but it would actually be wrong to use 10.0mm or 16.00mm)

 

[EFLImpudence]

Eric mentioned Earth Bonding, at seminars by NICEIC etc I have heard them say that the term is incorrect, the correct term is Bonding - Main Bonding.
I actually disagree with them - the term we were told to use a relatively hort few years ago was EEBADS (or EEBADOS).
Well to me as the words "Earth" and "Bonding" in those abbreviations were present together so why not, as a shortform, call it "Earth Bonding"?

It was actually "Earthed Equipotential Bonding..." if that makes a difference -
but it doesn't really matter because they did away with the term.

It connects robustly together all incoming services that can reasonably be expected to pick up a potential from the earth around us and we deliberately clamp it all together in equalise all these potentials as far as reasonably practicable. So, Gas, Water, Oil, pipes etc and any structural metal and the installation earth terminal (whether that is derived from/near to a substation that might sometimes be quite a distance away therefore quite a potential voltage away from the ground beneath our feet. Likewise large slabs of damp concrete too.
If someone uses the term "Earth Bonding" I would not take them to task with it.

If we Main Bond as one thing and all other sorts of bonding are supplementary bonding, you might be linking across several different pipes to, example, a boiler of some sort, additionally you might be linking to the c.p.c of some boilers and again you might be ling to the c.p.cs of other circuits in that location. That is all supplementary bonding, because it is bonding that is not main bonding. If we stick to the two terms we know it is bonding and which type it is, indeed we might have a IT system that has supp bonding but not have main bonding.

Surely it is better and less likely to deceive or be misconstrued for as to have just the two types? and if someone wants to call Main Bonding Earth Bonding instead then I can live with that and if someone calls it cross bonding instead of supp bonding then personally I will usually know what they mean but it should be recognised that there are only two types therefore really only those to terms be used when discussing bonding.

John said
"The sort of 'cross-bonding' I was thinking/talking about (a lot of which I inherited in my present house, many moons ago!) usually consists of the connecting together of pipes and other conductive things (like sinks/baths etc., not being part of the electrical installation), none of which are usually either exposed-c-ps or extraneous-c-ps."

I says, yes there may or there may not be c.p,cs connected but in either case it is supp bonding if it is not main bonding.
And I think EFLI is saying much the same thing as John too.

K.I.S.S. Main or supp you often have both.

Main Bonding is often 10.0mm or above.
Supp bonding is to be worked out by a little formula but hey using that formula and the rules with it then it often works out as 4.0mm or above.
There is usually nothing to stop you using one looped conductor of say 10.0mm or above to satisfy both functions if you prefer but it is not necessary either, it would probably render it more time consuming an more expensive too.

Again - What?

(Well I can`t think of a situation where 4.0mm supp bonding is required but it would actually be wrong to use 10.0mm or 16.00mm)

So?

 

[ebee]

It was actually "Earthed Equipotential Bonding..." if that makes a difference -
but it doesn't really matter because they did away with the term.

Agreed it was but folk called it Earth Bonding or sometimes Earthed Bonding too so yes you are correct.

PS I thought my post was one of my usual rambles so I tried to keep it slightly shorter - Well that`s my story and I`m sticking to it.

 

[EFLImpudence]

Agreed it was but folk called it Earth Bonding or sometimes Earthed Bonding too so yes you are correct.

It doesn't matter what people called it if it was wrong and meant something else.

Can you not see the difference?